Re: Boeing XRI Use Cases

Noah,

On 6-Aug-08, at 10:28 AM, noah_mendelsohn@us.ibm.com wrote:

> We agree, or at least we appear to:  the empty string is legal as an  
> IRI
> Reference and as a URI Reference.  The empty string is also a member  
> of
> the value and lexical spaces of the XSD anyURI datatype.  The the  
> empty
> string is also legal as the value of a namespace declaration in XML,  
> that
> string is a distinguished value that is in fact used to cancel the
> corresponding prefix binding.  Accordingly, there are no namespaces  
> named
> with the empty string.
>
>> Relative and "empty string"  IRI are certainly valid IRI, the
>> question is if they are valid "anyURI" in XML 1.1?
>
> I assume you mean XSD 1.1?  The specification says [1]:

Yes XSD 1.1 Draft 20

>
>
> "The ·lexical space· of anyURI is the set of possibly empty finite- 
> length
> character sequences."  Earlier it says:
>
> "[Definition:]   anyURI represents an Internationalized Resource
> Identifier Reference (IRI).  An anyURI value can be absolute or  
> relative,
> and may have an optional fragment identifier (i.e., it may be an IRI
> Reference).  This type should be used when the value fulfills the  
> role of
> an IRI, as defined in [RFC 3987] or its successor(s) in the IETF  
> Standards
> Track. "
>
> So, >any< sequence of characters, including the empty sequence, is a  
> legal
> xsd:anyURI.  The specification says that anyURI >should< be applied  
> when
> the string represents an IRI reference.  Conformance to IRI ref.  
> syntax is
> thus strongly encouraged, but not enforced by the datatype.
>
>> I discounted that as perhaps being non-normative given the
>> draft status and the other document.
>
So I conclude that contrary to http://www.w3.org/TR/xml-names11/ 
#reluri , the recommendation
http://www.w3.org/2000/09/xppa  is not making it into XSD 1.1?

Perhaps some mention should be made in http://www.w3.org/TR/xml- 
names11 that it is no longer authoritative.

I guess that makes the answer to Julian's original question.

No http://www.w3.org/TR/xml-names11/ is not "the namespaces  
specification for XML 1.1", http://www.w3.org/TR/xmlschema11-2/ should  
be used.

Regards
John Bradley
OASIS IDTRUST-SC
http://xri.net/=jbradley
五里霧中

> If we're discussing XSD 1.1, then [1] is as authoritative a source as
> you'll find.  The only Recommendation-level version of XSD is 1.0 [2].
> That version did try to enforce conformance to (pre-) IRI syntax, but
> clearly allows for relative and thus for empty forms.  I think there's
> very little question that XSD anyURI, whether 1.0 or 1.1,  allows  
> for IRIs
> (perhaps modulo some edge cases in 1.0 as you say that you and DaveO
> uncovered some), allows for relative IRIs, and thus allows for the  
> empty
> string.  We agree that the empty string is not and never has been  
> usable
> as the name for an XML namespace.
>
> Noah
>
> [1] http://www.w3.org/TR/xmlschema11-2/#anyURI
> [2] http://www.w3.org/TR/2004/PER-xmlschema-2-20040318/#anyURI
>
>
> --------------------------------------
> Noah Mendelsohn
> IBM Corporation
> One Rogers Street
> Cambridge, MA 02142
> 1-617-693-4036
> --------------------------------------
>
>
>
>
>
>
>
>
> John Bradley <john.bradley@wingaa.com>
> 08/06/2008 12:32 PM
>
>        To:     noah_mendelsohn@us.ibm.com
>        cc:     "Booth, David (HP Software - Boston)" <dbooth@hp.com>,
> "Henry S. Thompson" <ht@inf.ed.ac.uk>, Julian Reschke
> <julian.reschke@gmx.de>, www-tag@w3.org
>        Subject:        Re: Boeing XRI Use Cases
>
>
> Hi Noah,
>
> I don't claim to e an XML 1.1 expert.
>
> I was looking at Sec 2.2 of xml-names11:
> http://www.w3.org/TR/xml-names11/
>
>> 2.2 Use of IRIs as Namespace Names
>> The empty string, though it is a legal IRI reference, cannot be used
>> as a namespace name.
>>
>> The use of relative IRI references, including same-document
>> references, in namespace declarations is deprecated.
>>
>> Note:
>>
>> This deprecation of relative URI references was decided on by a W3C
>> XML Plenary Ballot [Relative URI deprecation]. It also declares that
>> "later specifications such as DOM, XPath, etc. will define no
>> interpretation for them".
>>
>
> I should have used "empty string" rather than null.
>
> There seems to be a conflict between the two documents.
>
> The reference to relative IRI XML schema re 3.3.18 of xmlschema11-2 is
> in a [Definition:]
>
> I discounted that as perhaps being non-normative given the draft
> status and the other document.
>
> Relative and "empty string"  IRI are certainly valid IRI, the question
> is if they are valid "anyURI" in XML 1.1?
>
> It is worth someone having a look at, but probably someone closer to
> it than me.
>
> However I don't think it is particularly relevant to XRI though I
> suppose  that relative XRI would also be prohibited according to xml-
> names1.1.   I don't think I am going to lose sleep over that:)
>
> The XRI specs don't rely on any new functionality in XML 1.1.
>
> Regards
> John Bradley
> OASIS IDTRUST-SC
> http://xri.net/=jbradley
> 五里霧中
>
>
>
>
> On 6-Aug-08, at 7:29 AM, noah_mendelsohn@us.ibm.com wrote:
>
>> John Bradley writes:
>>
>>> The definition of "anyURI" changes slightly to include the
>>> mapping of http: IRI according to RFC3987 This allows for the
>>> ireg-name component to be mapped via RFC3490 for schemes using
>>> domain names.
>>
>> OK, good.
>>
>>> In XML schema 1.1 that is almost done [http://www.w3.
>>> org/TR/xmlschema11-2/]
>>
>>> [...] allows almost all http: scheme IRI to work as "anyURI",
>>> relative and null IRI are excluded so it is still a sub set,
>>> though a much larger one than before.
>>
>> Hmm, I don't see where relative or "null" are excluded.   The
>> specification for that datatype says [1]:
>>
>> "[Definition:]   anyURI represents an Internationalized Resource
>> Identifier Reference (IRI).  An anyURI value can be absolute >>or
>> relative<<, and may have an optional fragment identifier (i.e., it
>> may be
>> an IRI Reference)."
>>
>> Was there something else you meant when you said that "relative [is]
>> excluded"?  I read this as explicitly allowing relative.  As to  
>> "null"
>> IRIs, the word null does not appear in RFC 3987 [1] or in RFC 3986
>> [2] for
>> that matter, but RFC 3987 includes the following grammar:
>>
>>  IRI-reference  = IRI / irelative-ref
>>
>>  irelative-ref  = irelative-part [ "?" iquery ] [ "#" ifragment ]
>>
>>  irelative-part = "//" iauthority ipath-abempty
>>                      / ipath-absolute
>>                      / ipath-noscheme
>>                      / ipath-empty
>>
>>  ipath-empty    = 0<ipchar>
>>
>> This seems to me to indicate that an IRI Reference, as required by  
>> XML
>> Schema 1.1, can indeed be an ipath-empty, I.e. the null string.  Am I
>> still missing something?
>>
>> Noah
>>
>> [1] http://www.ietf.org/rfc/rfc3987.txt
>> [2] http://www.ietf.org/rfc/rfc3986.txt
>>
>> --------------------------------------
>> Noah Mendelsohn
>> IBM Corporation
>> One Rogers Street
>> Cambridge, MA 02142
>> 1-617-693-4036
>> --------------------------------------
>>
>>
>>
>>
>
>
>